1. Field
The disclosed aspects relate generally to communications between devices and specifically to methods and systems for improving acquisition for near field communication (NFC) load modulation.
2. Background
Advances in technology have resulted in smaller and more powerful personal computing devices. For example, there currently exist a variety of portable personal computing devices, including wireless computing devices, such as portable wireless telephones, personal digital assistants (PDAs) and paging devices that are each small, lightweight, and can be easily carried by users. More specifically, the portable wireless telephones, for example, further include cellular telephones that communicate voice and data packets over wireless networks. Many such cellular telephones are manufactured with ever increasing computing capabilities, and as such, are becoming tantamount to small personal computers and hand-held PDAs. Further, such devices are enabling communications using a variety of frequencies and applicable coverage areas, such as cellular communications, wireless local area network (WLAN) communications, NFC, etc.
For near field communication (NFC), a target NFC device may communicate with an initiator NFC device using load modulation, (e.g., modulation of a carrier signal) by switching the load (e.g., the impedance of the Target) on and off Depending on which specification (NFC forum, ISO/IEC, ECMA and etc.) and depending on which modulation type (NFC type A, B, F, etc.), a known pattern/sequence at the beginning of a packet may be called a start of sequence (SoS), a start of frame (SoF), or a start of communication (SoC). Generally, SoS/SoF/SoC have poor auto-correlation property. The current acquisition algorithms are based on envelope detection and exhibit poor performance for detecting SoS/SoF/SoC, especially when the change in amplitude of the envelope is small due to inefficient coupling between a target NFC device antenna and an initiator NFC device antenna.
Thus, improved apparatuses and methods improving acquisition for near field communication (NFC) load modulation may be desired.